将GBK编码（ANSI的简体中文编码）转换为Unicode编码格式：

    QByteArray encodedString = "...";

    QTextCodec *codec = QTextCodec::codecForName("GBK");

    QString string = codec->toUnicode(encodedString);

将Unicode编码转换为GBK编码格式：

    QString string = "...";

    QTextCodec *codec = QTextCodec::codecForName("GBK");

    QByteArray encodedString = codec->fromUnicode(string);

下面给出读取GBK编码的TXT文件的示例代码：

    QFile file("FileName");

    QTextCodec *codec = QTextCodec::codecForName("GBK");

    QString line = codec->toUnicode(file.readLine());